Means for dually completing oil wells



June 8, 1954 F. DAVIS MEANS FOR DUALLY COMPLETING OIL WELLS 5Sheg'ts-Sheet 1 Filed Feb. 16, 1949 R m m W.

HTTEST Louis F. Davis BY mnM a 5M June 8, 1954 F. DAVIS MEANS FOR DUALLYCOMPLETING OIL WELLS 5 Sheets-Sheet 2 Filed Feb. 16, 1949 w Q Q Q INVENTOR.

mmmmmU Louis F. Davis BY rmaaw H TTES T Hl'tornej June 8, 1954 F. DAVISMEANS FOR QDUALLY COMPLETING OIL WELLS 5 Sheets-Sheet 3 Filed Feb. 16,1949 IN V EN TOR.

HTTEST was; a. 4

Louis F. Davis ,yWafM Attorney 5 Sheets-Sheet 4 INVENTOR.

Louis R Davis BY Ma -M Z Hzi'orney L. F. DAVIS MEANS FOR DUALLYCOMPLETING OIL WELLS .ET, 64 L 5 \v-\\ Av v JV \W M r17 VVVW. ////V /NV///M7 JZA/ m m w u m w mww m a m m.

June 8, 1954 Filed Feb. 16, 1949 June 8, 1954 DA s 2,680,408

MEANS FOR DUALLY COMPLETING OIL WELLS Filed Feb. 16, 1949 5 Sheets-Sheet5 FITTE'ST 6 INVENTOR. b 1144; 6% Louis F. D auz's BY fi MJMZ' 8,

H i'i'orney Patented June 8, 1954 Louis F. -l)avis,'Dallas, Texassi'gnor to The Al;-

lantic Refining Company, Philadelphia, Pa.,'a corporation ofPennsylvania "Application February 16, '1 9 19,"Serial No. 76,750

9 Claims.

This invention relates to an improved system for producing from aplurality of subterranean oil reservoirs. More particularly, theinvention relates to a system includin artificial lift meansfor-producing from a plurality of oil reservoirs through a single borehole without commingling of the fluids from the several reservoirs.

The search for oil has led to the discovery in certain oil fields of anumber of producing zones. Generally, the characteristics ofthes'e'producing zones are dissimilar and frequently both oil and asreservoirs are encountered. In the case of oil reservoirs, to which thepresent invention is primarily directed, the pressure exerted on the oilcontained therein may be attributable to a water drive, for example, orthe presence of dissolved gaseous hydrocarbons. Further, there may be aconsiderable variance in the quantumof pressure exerted on the variousreservoirs in the hold.

Joint production of oil from two or more 'producing zones through asingle casing, ortubing strin is likely to result in irreparable damage"of the reservoirs and wastage of the fluids contained therein due todrainage'of fluid from one reservoir into a reservoir of lesser pressureand the attendant pressure drive reduction the former. For theabove'reasons and the fact that in substantially all'States in whichoilis being produced from subterranean petroliferous zones laws havebeen enacted i posin restrictionson the production of oil and gas, oreither, as the case may be, from two or more producing zones in an oilfield, efforts have been directed to the development of a method andapparatus for independently producing oil from a plurality of overlyingreservoirs.

Obviously, this could be accomplished by producing separately each ofthe reservoirs through a well or wells communicatin solely therewith;however, relatively high'drilling' costs make desirable the productionfrom the producing zones through a single bore hole. I In this regard,little difficulty is experienced in the 'case of reservoirs havingsufficient pressure exertedfthereonfby a water drive, for example, toproduce the same without employment of artificial lift means. For thispurpose a tubing strin having'a packer provided on the end thereof isrun'into a bore hole which traverses the reservoirs and is lihed with awell casing having, perforations therein "communicating with each of thereservoirs. The

well packer is set intermediate an upper and lower plCdllClllg'ZOIle,whereby'fluidffrom the upper producing zone will flow 'intothe 'we11easing and thence to the well'surface through the 'therethrbugh 'to'th'ewell surface. As the reservoirs are produced, the reservoir pressureswill be reduced and-this will continue until the pressure drives areinsufiici'ei-it to cause fluids co-ntamed therein to flow to the wellsurface. Natural flow having ceased, the reservoirs may then be put onartificial lift to recover an additional amount of reservoir fluid. Thesame situation obtains in the case of reservoirs in which the initialpressure is insufficient 'to permit natural flow of reservoir fluid.

A modification of the system described above, which has been proposedfor producing separately from two or more reservoirs having pressuressuch as to require artificial lift means, utilizes gas lift valvesoperable upon the establishment of a preselected differential inpressure thereacross. In this system, an inner tubin strin is run insidethe outer tubing string ina manner to provide an annular spacetherebetween and a packer is set externally of the inner tubing strinand adjacent the lower end thereof, in a manner sealing the'annu-larspace between it and the outer tubing string, whereby reservoir fluidfrom the lower reservoir instead of flowing upwardly in the outer tubingstring, as in the previous system, will be directed up wardly into theinterior of the inner tubing string. Pairs of'opp'ositely'clisposedgas'lift valves are provided at spaced intervals respectively in thewallsof the inner and outer tubing strings for lifting independentlyreservoir fluid frofn the lower reservoir and the upper reservoir,respectively, The gas lift valves maybe actuated by injection of gasunder pressure into the annular space between the innerand outertubingstrings. The valves are adjusted so as to be actuated by decreasingpressure differentials from the uppermost down to the lowermost pair ofvalves. The gas is injected at apressure sufficient to. actuate theuppermost pair of valves whereby the gas will .pass therethrough andvlift to the well surface the reservoir fluids above the uppermost pairof valves. in a similar manner, succeeding pairs of gas lift valves areactuated until the reservoir fluidsabove the lowermost pair of gas liftvalves have been raised to the well surface. In

practice, this system is unsatisfactorybecause the gaspressureatwhichthega's liftvalvesare actuated is dependent uponyth'e'pressuresof the reservoir fluids in the annular space between the outer tubingstring and the casing, on the one hand, and within the inner tubingstring, on the other hand, and, therefore, only partial control of thissystem from the well surface is possible.

The present invention is concerned with an improved system for producingfrom a plurality of subterranean oil wells and utilizes pressureresponsive valve means of the intermitter type for lifting production tothe well surface. The pressure responsive valve means are provided atvertically spaced intervals in the wall of the first and second tubingstrings. It is necessary to maintain at all times the reservoir liquidsin the annular space between the casing and first tubing string andwithin the second tubing strin at substantially the same level. For thispurpose there is connected in the second tubin strin below the lowermostpressure responsive valve means a valve for controlling the level of thereservoir liquid normally standing in the second tubing string. By meansof this improved system a plurality of producing zones may be producedthrough a single bore hole without commingling of the fluids from theseveral zones.

Other systems have been proposed for producing independently a pluralityof producing zones through a single bore hole but none of them areentirely satisfactory for various reasons.

Accordingly, one object of the invention is to provide an improvedsystem for producing from a plurality of subterranean reservoirs througha single bore hole, and a system that will obviate the difficultiesabove set forth.

Another object of the invention is to provide a system for producingfrom a plurality of producing zones through a single bore hole withoutcommingling of the fiuids from the several zones.

A further obpect is to provide a system for producing from a pluralityof producing zones through a single bore hole, which system includesartificial lift means for lifting independently to the well surfaceproduction from the several zones.

A still further object is to provide such a system in which means areprovided for controlling the level of production in the well from one ofthe producing zones.

Other objects and features of the invention will be apparent from thedrawings and description which follow.

Figure 1 is an elevational view, partially in section, showing a systemconstructed in accordance with the invention and including pressureresponsive valve means for lifting independently to the well surfacefluid from a plurality of reservoirs. ii Figure 2 is another embodimentof the invention in which pressure responsive valve means are employedfor lifting to the well surface production from one of the producingzones and mechanically actuated valve means for lifting to the wellsurface production from another of the producing zones.

Figure 3 is an elevational view, partially in section, showing in detaila suitable gas lift valve for lifting reservoir liquid to the earthssurface.

Figure 4 is a sectional view taken along the line 4-4 of Figure 3.

Figure 5 is an elevational view, partially in section, showing in detaila suitable mechanically operated lift valve.

Figure 6 is a sectional view taken along the line 6-B of Figure 5.

Figure 7 is a sectional view taken along the line l'! of Figure 5.

Figure 8 is an elevational view, partially in section, showing asuitableliquid level control valve.

Referring to the drawings, and in particular at this time to Figure 1,the earths surface is designated generally by the numeral I. A well boretraversing an upper oil reservoir 2 and a lower oil reservoir 3 is linedwith a well casing 4 which is provided with suitable perforations 5 and6, adjacent reservoirs 2 and 3, respectively. A first tubing string l isdisposed within casing :3 in a manner to provide a first annular space 3therebetween. A conventional permanent type packer 9 is secured betweencasing 4 and tubing string i, and intermediate of reservoirs 2 and 3. Asecond tubing string in is disposed within first tubing string 1 in amanner to provide a second annular space it therebetween, and a suitableanchor packer I2 is secured between tubing strings I and H! and adjacentthe lower ends thereof. By this arrangement reservoir liquids fromreservoirs 2 and 3 are directed into first annular space 8 and theinterior of second tubing string ill, respectively. It is obvious thatconditions'lrequently may arise where it would be desirable to employ aremovable type packer in place of permanent type packer 9 and also ahook wall packer in place of anchor packer l2 and it is to be understoodthat such arrangement is within the scope of this invention.

It is the purpose of this invention to provide artificial lift means ofthe intermitter type for lifting independently to the earths surface 1reservoir liquids from reservoirs 2 and 3 in the event that the pressuredrive of the reservoirs, or either, as the case may be, is insufficientfor this purpose. To this end pairs of pressure responsive valve meansI3, [4, and [5 are provided at spaced intervals in the walls of tubingstrings l and ii], the pairs of pressure responsive valve means beingresponsive to progressively decreasing pressures from the uppermost pairof pressure responsive valve means i3 to the lowermost pair of pressureresponsive valve means 15. The pressure responsive valve means, whichwill be described more fully hereinafter, may be of the conventionaltype of intermitter gas lift valve operable upon application of apredetermined fluid pressure to the input side thereof to thereby permitthe fluid to flow therethrough and lift to the earths surface liquidstanding thereabove in the well. Such a device is disclosed, forexample, in U. S. Patent No. 2,385,316, issued to R. O. Walton onSeptember 18, 1945, and entitled Well Flow Device."

Any suitable means, not shown, may be employed for intermittentlyintroducing into annular space H through valve controlled pipe 116 fluidunder pressure sufiicient to actuate the several pairs of pressureresponsive valve means, whereby the fluid is permitted to flowtherethrough and lift to the earths surface i the reservoir liquids infirst annular space 8 and in second tubing string Ifl above thelowermost pair of pressure responsive valve means IS. The reservoirliquids from annular space 8 and tubing string to pass through valvecontrolled pipes l1 and 18, respectively, to suitable storage tanks, notshown.

For reasons which will be obvious from the description hereinafter, itis necessary to maintain the reservoir liquid in annular space 8 andsecond tubing string ill at substantially the same face.

:..l rc1- Accordingly, thereis connected ;inzsegnd etubin strinLIL-below th l w rmost pr s re :re-

spon iv valve mean It liquid level controivalve "means :LQ-forcontrollin the l ve of reservoir l quid :n rmallyostandine in s nd tubinstrin ;,.L0- h l quid l vel ,.control valve means, which zwillbedes ribd in detail hereinaft r, may e o 1 conventional type, such as thatdisclosedrin Patent ,No. i2,597,193, issuedMay .20, 1952,11i0 Horace M.,Sta gs and Louis Davis.

in practice, due to thesizes of standard pipe wh chflare employedusually :in dualcompleti n lations, the normalliquidlevel in secondnestling L0 is above that of the liquidin first annularspace. ,8,regardless of. the fact that reseryoir' 25 may be somewhat moreproductive th n reservoir ,3. should level control valve in second,tubingstring .21 li he; liquid standing in the tubing string may bmaintained at the same levellas thatof the ,l -i q. u id';in firstannular space -8. In some in- Therefore, by suitably placin stances,however, the rate of flow of liquid from -uppcrpr duc ng r s rvoir-2 maybe o mu h greater than that from lower reservoir 3, or the tubin em oyedin: the w ll may esuch; that th liquid- -level in first annular space ,8is at a level L gherthanthatof the liquid in secondtubing -I-l. Insuchinstances, in orderto maintain quidlevels-in the well equal,asuitable, conventional flow direction means or crossover pa ker ma bemployed and dispos d in t well annersuCh that liquid from upperreservoir directed into second tubing string ii) and liquidzfromlowerproduclngreservoir 3 is directed into first annular space 8. It isreadily seen that liquid level control means 19 disposed in secondtubingstring it} then may be adjusted in a manner to maintain the liquid levelin tubing I string Id, at the same height as the liquid level in firstannular space 8.

.EigureZ-shows-another embodiment of theinvention which differs fromthat ofFigure 1 in -,that there issubstitutcd forthe'pressure-responsive valve means i3, I4, and IE on second tubingstring l0 a mechanically, actuated lift-device connectedin tubing stringlllabove liquid levelconlJ IQl valve means l9 for periodically injecting,iiuid into the reservoir liquid standing in the tubing stringto raisethe liquid to {the well sur- One such device, commonlyv termed anv,sintermitter is disclosed in U. S. Patent No. 1 1,683,930, ,issuedtoHorace M. Staggs 0n September ll, 1928, and-entitled Air-eLiftPump. Theintermitter, 29, which-is described in detail below, is disposed,asshown, inosecond tubing string In and is actuated by means of a weight2.!

lperiodicallybrought into contact with cap '22 of the-intermitter,weight2l being alternately raised andlowered'by means of a suitableraising and lowering mechanism 23 located on the earths, surfaceland towhich the weight isoperatively i connected by means of wire: line 24.

A suitable gas lift device, connected, for extainedinaseated. position,on valvelseatgis ;.by;:a pressure. differential that existsthereacross,-.:the

pressurelbeing greater from below, suitablysprovided about'main valvestem 30 connected ;.to

valve 28. Whenvalve I28 is;.opened,,a :manner described hereinafter, the:fiuidgin the :lower end of, housing :25 will flow pupwardly pastvalves/28 into chamber 34 and thence will pass through-a series of ports32Hformed in the wall of housing .15 into the .interior,-,.of second"tubing string 19.

The fluid passing out of the valve will lift tothe wellsurfacereservoirliquid standing in tubin string is above the valve.

For opening valvex28 there is provided bellows o stem .33, which isconnected at one of its ends-to floating head :34 and the free end ofwhich is .adapted to contactzthe end of valve stemrz3 8' :in1a

cessive. sections of housingiis and is provide'dwith an axial opening33in which bellows stem 33 is mounted for slidable movement. Whenbellows 35 is contracted by, the pressure of fluidionrthe exteriorthereof, as described hereinafter, floatinghead 3 and, therefore,bellows stem 33,- will be. caused to move downwardly whereby bellowsstem ,33 will impinge upon valve estem13lln0pcning valve 28 andpermittingfiuid in the lower part of, housing 25 to flow pastthe valve"and into vsecond tubing string Hi through ports,.32, .as-describedhereinbefore.

Forcontrolling the pressure of fluid on thereaterior of bellows 35and'thustheopeningofvalve 28, there isprovided in theupper end f housing25. secondary valve 39 WhlCh'iS actuated-bypilot bellows 40. Bellowsiii] is secured at oneiof its ends to fixed head 4! providedxatthe uperl'end of housing 25, and terminates at its lower end-in floating head42 which "normally rests against plate 43 closing one end of bellowshousing '55,

which isconnected atits other end to fixed head 4!. Secured to floating,head 4.2 and extending through a suitable aperture 45 in plate-43 0fbellows housing is secondary valve stem 45. Valve 39 is normallymaintainedina closed position'by means of helicalspringifil'l'whichisprovided about valve stem 46 and-which is distendedbetween plate 43 of bellows housingAiand adjustment nut 48 threadedon-valve stem dlip Valvefig is adapted to be seated normally on valveseat 49 which is threaded or otherwise securedin coupling 55} connectingsuccessivesections of housing, 2.5 and carryinga conventional ball checkvalve 5! for closing passage 52 inqvalve seat la-against fluid pressurefrom belowl It is readily seen that fluid in second annularzspace l I,as well as entering into-the lowerpartbf housingze through nipple28,will pass through nipple 27 into the upper end-of the housing butnormally will be, prevented from passing downwardly through passage 52by valve 35-3. The fluid, however, enters bellowshousing 44 throughrad-ial ports siiprovided therein and impinges upon the exterior ofpilot bellows flll thereby causing the bellows to contract against thepressure I of spring 41, thus opening valve 33. The-fluid then,passesthrough opening'52 in .valve seat-.43, past ball check valve 5|,and through passages 54 provided'in coupling50 into that portion-ofhousing 25 containingbellowsr35; thelpressure-of gas: lift; device,causes 1 bellows 35, to contrao t,

- by threaded couplings thereby opening valve 28, as describedhereinbefore. When the pressure in second annular space I I hasdecreased to a predetermined value by the passage of fluid through ports32-, the fluid pressure exerted on the exterior of pilot bellows 49 willbe insufficient to maintain the bellows in a contracted position;therefore, the force of helical spring 41 will cause valve 39 to close.This is followed by the closing of main valve 28 which 1 results whenthe fluid pressure exerted on the exterior of bellows decreases below avalue sumcient to maintain bellows 35 in a contracted position due tothe escape of the fluid out of bleed ports formed in housing 25. It isreadily seen that by proper adjustment of nut 48, valve 28 may be causedto be seated or closed when the fluid pressure in second annular spaceII falls below a predetermined value.

The intermitter 29 of Figure 2, shown in detail in Figures 5, 6, and 7of the drawings, comprises generally housing 56 secured at its oppositeends to successive sections of second tubing string I9 Valve stem 58carrying valve 59 is mounted for slidable movement within sleeve 89secured within axial bore 5i in housing 5% by threaded collar 62. Valve59 is seated as at 63 and is normally maintained in a closed position bythe action of helical spring 6 distended between shoulder 65 of housing56 and shoulder 66 of cap 61 threaded to stem 58 of I valve 59. Fluidunder pressure in second annular space II is normally maintained againstthe pressure side of valve 59 through interconnecting port 68 andchamber 99. However, upon the opening of valve 59 the fluid will bepermitted Valve 59 is mechanically operated intermittently 4 'by thelowering of weight 2! against cap 22, the

action of weight 2I being controlled through the 'medium of wire line 25and lowering and raising -mechanism 23 located at the earths surface I,

as stated hereinbefore.

The liquid level control valve of Figures 1 and 2 is shown in detail inFigure 8 and comprises generally a housing formed of end sections '19and threaded as at Bi and 82, respectively, to

central section 83, and as at 8 t and 35, respectively, to successivesections of second tubing string I0. Valve 86 is seated as at 8'? onseat member 99 rigidly secured within end section 83 by threaded collar89, which collar also serves as a guide sleeve to valve stem 9-6 throughaxial bore 9I and to provide a series of vertical bores or ports 92 forthe passage of fiuid therethrough. Valve 86 is normally maintained in aclosed position by helical spring 93 distended between flanged collar 94and nut 95 threaded on the free end of stem and rigidly secured thereonby 'lock nut 96. Bellows 9? is secured by welding,

or in any other suitable manner, as at 98, to floating bellows head 99and as at I99 to fixed bellows head I91, the fixed head being rigidlysecured as by threading at I02, in one end of cylinder $93 which, inturn, is threaded at its opposite end to flanged member I99 of endsection '19 and in a manner providing sealed bellows chamber I andannular space I96 therebetween and the inner wall of central section 83.

Bellows stem I0! is threaded to bellows head 99 and adjacent itsopposite end is mounted for slidable movement through axial bore I08 incap I09 threaded into bellows head lIlI. A series of bores or ports H0in cap E99 permit the flow of liquid into and from the interior ofbellows 9?. Cap III is threaded to the free end of bellows stem I07 andupon compression of bellows 9'! will be caused to move downwardly withstem IIll against cap H2 and through the medium of stem 96 to open valve86. It will be seen that when bellows 91 is in a distended position, capI I I is brought to rest against cap H2 but that liquid within space H3within central section member 83 is at all times free to flow into andfrom the interior of bellows 91 through openings H4 in cap III, andports H0 and annular groove H5 in cap I99. It furthermore will be seenthat opening movement of valve 86, and, consequently, the compression ofbellows 97, is limited by cap H6 threaded into end section 80.

Upon the opening of valve 86 liquid entering through strainer H7 will becaused to flow by reservoir pressure through openings H8 in cap H6, pastvalve 36, through ports 92 in space H9 in central member 83, and throughannular space I06 from which it will flow through interconnecting portsH9 and I29 into tubing I9 to a predetermined level above the liquidlevel control means. Also, the reservoir liquid entering the liquidlevel control means will be caused to enter the interior of bellows 91through ports H4 and H9, and annular groove H5, and thus to exert apressure against the interior of bellows 93 dependent upon the level ofthe liquid in tubing I0 above the liquid level control means, as againstthe pressure of the fluid in annular space H, which is applied againstthe exterior of bellows 91 through interconnecting ports 12! and I22providing communication between annular space H and bellows chamber I65.

Upon removal of the reservoir liquid in tubing is by the artificialmeans associated therewith, a differential in pressure across bellows91' in favor of the pressure of the fluid in annular space H will bebrought about whereby bellows 9? will be compressed and cause bellowsstem I97 to be moved in a downwardly direction against cap I I2 andvalve stem 98, thereby causing valve 86 to be opened and to admitadditional liquid to tubing Hi to the predetermined level at which timethe differential pressure across bellows 91 will be reversed in favor orthe pressure of the liquid against the interior of the bellows and valve86 closed.

Referring to Figure 1, a description of the operation of the inventionwhen employing pressure responsive valve means on both tubing strings Iand Ill will now be made. The several pairs of pressure responsive valvemeans provided at spaced intervals in the walls of the tubing stringsare adjusted to respond progressively to decreasing pressures from theuppermost pair of pressure responsive valve means I3 to the lowermostpair of pressure responsive valve means 5. The apparatus is thenassembled in the well, as shown in Figure 1, with the liquid levelcontrol means i9 connected in second tubing string I0 at a position suchthat the level of reservoir liquid therein is maintained substantiallyat the same level as that of the liquid contained in first annular space8. When the apparatus is assembled initially liquid will be entrapped insecond annu- 75' larspace II. Fluid under pressure sufficient toate-6,468

9, eaters-an of the pressure responsive vane-means is introduced theninto second annular space I! through valve' controlledpipe s; at thispoint each of the pressure responsive valve means will open permittingreservoir liquids within second annular space II" to pass th'erethroughinto first annularspace S; and second tubing string I0. When theinterface between the reservoir liquid and the fluid in second annularspace I I reaches the uppermost pair of pressure responsive valve meansI3 fluid will pass therethrough intofirst annular space 8 and secondtubing string It] to thereby lift to the well surface reservoir fluidscontained therein abovetl'ie uppermost pair of pressure responsive valvemeans I3. The passage of gas through the uppermost pressure responsivevalve means I3 will result in a decrease iii-the fluid pressure insecond'annular space II, as described liereinbefore, to the pressure atwhich this pair of valve means has been adjusted to close. This reducedfluid pressure will be maintained until the interfacebetween thereservoi'r liquid and the fluid reaches the next succeeding pair ofpressure responsivevalve means I4 which has been adjusted by means ofadjustment nut 48, as described hereinbefore, to close at a pressureless than that at which the uppermost pair of pressure responsive valvemeans ['3' closes. When the interface hasreached this point, fluid willpass through the pair of valve means I4 into first annular space 8 andsecond tubing string I I, lifting the reservoir liquid there in abovethe pair of valve means I4 to the well surface and resulting inadecrease in the fluid pressure-in second annular space II to the closingpressure of valve means Hi. This action will be continued until thelowermost pair of pressure responsive valve means has been actuated andthe reservoir liquids'thereabove in first annular space 8 and 'se'condtubingstring Hl' have been raised to the well surface; at'which time theintroduction of fluid into secondannular space Iii; through valvecontrolled pipe I6 is interrupted. The introduction of fluid into secondannular space II may be accomplished either manually or automatically bythe time-control mechanism, for examplev The flu-id is supplied tosecond annular space II until reservoir liquid in' flrst annular space8and second tubing string l above thelowermost pressure responsive valvemeans IEhas' been reached to-the well surface, at which time the supplyisinterrupted. Sufficient time is-allowed for the reservoir liquids toreach their normal standing leveliri' the well before the fluid isagain-injected into second annular space II to once again actuatethe"liquid level control valves'and lift to the; well surface liquidstanding in the well above the valves.

If theliquidin tubihg string l0 and the liquid in'first annular space Eare not maintained at substantially" the same level, only those pressureresponsive valvemeanswhich"'are'assoeiated with the-liquid atthe lowerlevel will operate to lift liquid tothe' well surface. Thus} forexample; if the liquid intubingst'ring Ianorinally'stands at a levelabove the uppermost pressure responsivevalve means I 3, and the liquidinfirst' annular space 8"standsnormally at a level between valve means Iland I55 when fluid under pressure sufficiei'i't-to actuateall of thepressure responsive valve means isintroduced into second annular space Ithe pressure ofthe fluid will decrease rapidlyitoa point belowtheclosingpressure of pressure responsive valve' means I4 whichpressureis belowthe closing pressureof valve means l3, due to thepassageof tl'ie fluid through the pressure, responsive valve means I4disposed in first tubing string I and'into the first annular space 8.Although, obviously, valve means I3 and I I will close almostimmediately, the fluid pressure in second annular space I I will besufficient to maintain the lowermost pair of valve means I5 open, and,therefore, the fluid will pass through the one ofthe pair of valve meansI5 which is disposed in first tubing string 7, to lift the liquidstanding in first annular space 8 above the valve means to the wellsurface. However; due to the hydrostatic head of the liquid in secondtubing string I0 above the lowermostjvalve means I5, the fluid pressurewill be insufii cient to lift such liquid to the well surface,

In view of the above, it is necessary to maintain at all times thereservoir liquids in first annular space 8 and second tubing string IIat substantially the same level. This is accorn plished, as pointed outhereinbeiore, by suitably disposing liquid level control valve meansI9'in second tubing string, H3.

Operation of the embodiment of the invention shown in Figure 2 issimilar to that of the system shown in Figure l, with the exception thatintermitter 2B is not actuated by the fluid pres sure, but instead bythe periodic lowering of weight M against cap 22 of the intermitter, asdescribed above. The raising and lowering mechanism 23 located at theearthfs surface is adjusted in a manner so that intermitter 2 0 iscaused to operate after each unloading o f liquid in first annular spaceSby operational the associated pressure responsivevalve means. Inthisembodiment liquid level control valve means I8 functions to maintain theliquid in second tubing string H) at a level such'that the pressure ofthe fluid in second annular space It is suflicientto cause the liquid intubing string 10 above inter; m itter 2d to be lifted to the'earthssurface. If the liquid entering tubing string Ill is permitted to risewithout control the hydrostatichead of the liquid above the intermitterin many instances would be so great as to prevent the unloading of theliquid by fluid passing through the intermitter from second annularspace I I.

The fluid introduced periodically into second annular space I I forlifting the reservoir liquidto the earth's surface may be any suitable,available gaseous medium; however, it-is preferable to em-' ploynormally gaseous hydrocarbon mixtures obtained, for examplairom nearbygas wells.

1' claim:

1'. In a well producing from a plurality of oil another of thereservoirs is directed into the in terior of the second tubingstrin'gthe cornbina'- tion therewith of marinate]; ommrvaivesoperatively secured to each of the tubing strings for controllingadmission ofliftingfluid'under pres sure into the first annular spaceand thesecorid tubing string, and liquid'level-control valve meansconnected-fin onecisaid tubing strings for con; trolling the normallevel of" production therein;

2. In a well producing from a plurality of oil reservoirs including awell casing communicating with each of the reservoirs, a first tubingstring disposed in the casing in a manner to provide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular spaceswhereby production from one of the reservoirs is directed into the firstannular space and production from another of the reservoirs is directedinto the interior of the second tubing string, the combination therewithof pairs of intermitter control valves responsive to lifting fluidpressure within the second annular space and provided at verticallyspaced intervals respectively in the walls of the first and the secondtubing strings for controlling admission of lifting fluid under pressureinto the first annular space and second tubing string, and liquid levelcontrol valve means connected in said second tubing string forcontrolling the normal level of production therein.

3. In a well producing from a plurality of oil reservoirs including awell casing communicating with each of the reservoirs, a first tubingstring disposed in the casing in a manner to provide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular spaceswhereby production from one of the reservoirs is directed into the firstannular space and production from another of the reservoirs is directedinto the interior of the second tubing string, the combination therewithof pairs of intermitter control valves responsive to lifting fluidpressure within the second annular space and provided at verticallyspaced intervals respectively in the walls of the first and the secondtubing strings for controlling admission of lifting fluid under pressureinto the first annular space and second tubing string, means forperiodically admitting lifting fluid into the second annular space at apressure sufficient to actuate the intermitter control valves, andliquid level control valve means connected in said second tubing stringfor controlling the normal level of production therein.

4. In a well producing from a plurality of oil reservoirs including awell casing communicating with each of the reservoirs, a first tubingstring disposed in the casing in a manner to provide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular spaceswhereby production from one of the reservoirs is directed into the firstannular space and production from another of the reservoirs is directedinto the interior of the second tubing string, the combination therewithof pairs of intermitter control valves responsive to lifting fiuidpressure within the second annular space and provided at verticallyspaced intervals respectively in the walls of the first and the secondtubing strings for controlling admission of lifting fluid under pressureinto the first annular space and second tubing string, means forperiodically admitting lifting fluid into the second annular space at apressure sufiicient to actuate the intermitter control valves, andliquid level control valve means connected in the second tubing stringfor maintaining normally well liquid in the second tubing string at thesame level as well liquid in the first annular space.

5. In a well producing from a plurality of oil reservoirs including awell casing communicating with each of the reservoirs, a first tubingstring disposed in the casing in a manner to provide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular spaceswhereby production from one of the reservoirs is directed into the firstannular space and production from another of the reservoirs is directedinto the interior of the second tubing string, the combination therewithof pairs of intermitter control valves responsive to lifting fluidpressure within the second annular space and provided at verticallyspaced intervals respectively in the walls of the first and the secondtubing stringsfor controlling admission of lifting fluid under pressureinto the first annular space and secondtubing string, means forperiodically admitting ifting fluid into the second annular space at apressure sufficient to actuate the intermitter control valves, andliquid level control valve means connected in the second tubing stringfor maintaining normally well liquid in the second tubing string at thesame level as well liquid in the first annular space, the pairs ofintermitter con-- trol valves being responsive to progressivelydecreasing pressures from the uppermost pair of intermitter controlvalves to the lowermost pair of intermitter control valves whereby fluidfrom the second annular space will be admitted substantiallysimultaneously through the uppermost pair of intermitter control valvesinto the first annular space and second tubing string and will lift thewell liquid therein above the levels of the respective uppermost pair ofintermitter control valves to the earths surface and progressively willbe admitted through succeeding pairs of intermitter control valves tolift the well liquid thereabove to the earths surface until the wellliquids in the first annular space and the second tubing string abovethe lowermost pair of inter-v mitter control valves have been lifted tothe earths surface.

6. In a well producing from a plurality of oil reservoirs including awell casing communicat ing with each of the reservoirs, a first tubingstring disposed in the casing in a manner to pro vide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular spaceswhereby production from one of the reservoirs is directed into the firstannular space and production from another of the reservoirs is directedinto the interior of the second tubing string, the combination therewithof intern litter control valves responsive to lifting fluid pressureWithin the second annular space and provided at vertically spacedintervals in the wall of the first tubing string for controllingadmission of lifting fluid under pressure into the first annular space,a mechanically operated intermitter control valve positioned within thesecond tubing strong for controlling admission of lifting fluid underpressure into the second tubing string, and liquid level control valvemeans connected in the second tubing string for controlling the normallevel of well liquid therein.

'7. In a Well producing from a plurality of oil reservoirs including awell casing communicating with each of the reservoirs, a first tubingstring disposed in the casing in a manner to provide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular spaceswhereby production from one of the reservoirs is directed into the firstannular space and production from another of the reservoirs is directedinto the interior of the second tubing string, the combination therewithof intermitter control valves responsive to lifting fluid pressurewithin the second annular space and provided at vertically spacedintervals in the wall of the first tubing string for controllingadmission of lifting .fluid under pressure into the first annular space,a mechanically operated intermitter control valve positioned within thesecond tubing string for controlling admission of lifting fluid underpressure into the second tubing string, means operable from the earthssurface to periodically actuate the mechanically operated intermittercontrol valve, and liquid level control valve means connested in thesecond tubing string for controlling the normal level of well liquidtherein.

8. In a well producing from a plurality of oil reservoirs including awell casing communicating with each of the reservoirs, a first tubingstring disposed in the casing in a manner to provide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular space wherebyproduction from one of the reservoirs is directed into the first annularspace and production. from another of the reservoirs is directed intothe interior of the second tubing string, the combination therewith ofintermitter control valves responsive to lifting fluid pressure withinthe second annular space and provided at vertically spaced intervals inthe wall of the first tubing string for controlling admission of liftingfluid under pressure into the first annular space, means forperiodically admitting fiuid into the second annular space at a pressuresufficient to actuate the intermitter control valves, a mechanicallyoperated intermitter control valve positioned within the second tubingstring for controlling admission of lifting fluid under pressure intothe second tubing string, means operable from the earth's surface toperiodically actuate the mechanically operated intermitter controlvalve, and liquid level control valve means connected in the secondtubing string for controlling the normal level of well liquid therein.

9. In a Well producing from a plurality of oil reservoirs including awell casing communicating with each of the reservoirs, a first tubingstring disposed in the casing in a manner to provide a first annularspace therebetween, a second tubing string disposed in the first tubingstring in a manner to provide a second annular space therebetween, andpacking means provided in the first and the second annular space wherebyproduction from one of the reservoirs is directed into the first annularspace and production from another of the reservoirs is directed into theinterior of the second tubing string, the combination therewith ofintermitter control valves responsive to lifting fiuid pressure withinthe second annular space and provided at vertically spaced intervals inthe wall of the first tubing string for controlling admission of liftingfluid under pressure into the first annular space, means forperiodically admitting fluid into the second annular space at a pressuresufficient to actuate the intermitter control valves, a mechanicallyoperated intermitter control valve positioned within the second tubingstring for controlling admission of lifting fluid under pressure intothe second tubing string, means operable from the earths surface topcriodically actuate the mechanically operated intermitter controlvalve, and liquid level control valve means connected in the secondtubing string for controlling the normal level of well liquid therein,the intermitter control valves being responsive to progressivelydecreasing pressures from the uppermost intermitter control valve to thelowermost intermitter control valve whereby the fiuid will be admittedthrough the uppermost intermitter control valve to the first annularspace and will lift the well liquid therein above the level of theintermitter control valve to the earths surface and progressively willbe admitted through succeeding intermitter control valves to the firstannular space and will lift the well liquid thereabove to the earthssurface until the well liquid in the first annular space above thelowermost intermitter control valve has been lifted to the earthssurface.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,968,633 Boynton July 31, 1934 2,006,909 Boynton July 2, 19352,298,834 Moore Oct. 13, 1942 2,385,316 Walton Sept. 18, 1945 2,391,605Walton Dec. 25, 1945

